Radio-wave excess could point to dark matter

An excess of radio waves recorded by a balloon-borne experiment could be a signal of dark matter, a new study suggests. Data from the ARCADE mission seem to fit in with other direct, recently reported evidence for dark matter, although some believe they may have a mundane explanation.

Dark matter is an elusive substance thought to make up more than 80% of the matter in the universe. While dark matter is invoked to explain the anomalous rotational velocity of galaxies and other mysterious astronomical phenomena, no-one has yet detected it conclusively. In recent years, however, hints of detections have been reported by several experimental collaborations, namely CRESST and DAMA at the underground lab in Gran Sasso, Italy, and CoGeNT at the Soudan mine in Minnesota, US. Other secondary evidence for dark matter has been reported by the satellite-borne experiment PAMELA and possibly the balloon-borne experiment ATIC – both of which have looked for excesses of electrons and positrons generated by dark-matter collisions.

Surfeit of radio waves

Now, it seems there may be secondary evidence from another balloon-borne experiment to add to the mix. In 2009 the ARCADE 2 collaboration reported that their experiment, which had taken radio measurements of the sky at frequencies between 3–90 GHz, had recorded a directionless or "isotropic" component of radio waves that was five to six times higher than contributions recorded in other surveys. Since then, studies have attempted to explain the excess as the remnant of, for example, supernovae or quasars, but none of these explanations has worked out.

Now, Nicolao Fornengo of the University of Turin in Italy and colleagues believe that the most likely explanation of the ARCADE excess is the existence of lots and lots of very faint sources, rather like the make up of "haloes" of dark matter outside galaxies. When dark-matter particles – known as weakly interacting massive particles, or WIMPs – collide and annihilate one another, they are thought to generate electrons and positrons, which subsequently generate radio waves via synchrotron emission as they travel through magnetic fields.

If such WIMPs were the root of the ARCADE radio excess, say Fornengo and colleagues, they would probably be quite light, with a mass between 10–20 GeV. That's "in the right ballpark of DAMA, CoGeNT and CRESST," says Fornengo. The results are due to be published in Physical Review Letters.

"Messy astrophysics"

Opinion is mixed among astrophysicists on how likely the researchers' dark-matter interpretation is. Douglas Scott at the University of British Columbia thinks a mundane interpretation is more likely. "If we're missing something, then the most likely candidate is that it's something to do with 'messy astrophysics' – i.e. details of the formation and evolution of galaxies," he says. "But it's worth keeping an open mind to the possibility that this is telling us something about particle physics and the nature of dark matter."

Alan Kogut, leader of the ARCADE collaboration at NASA's Goddard Space Flight Centre in Maryland, US, is "a little sceptical of any astrophysical result involving dark-matter annihilation", although he admits that the explanation fits. The Square Kilometre Array (SKA), a huge radio telescope in development in the southern hemisphere, should be able to provide corroboration, he adds.

Fornengo agrees that the SKA will shed more light on the ARCADE excess, and that an independent estimate of the universe's total isotropic radio background is needed. In the meantime, he likes the dark-matter interpretation because it "can reproduce the radio observations in a natural way, namely without introducing any further particularly optimistic assumption".

"I think it is an interesting exercise, and a suggestive one, but there a number of parameters that could entirely change the interpretation," says Stefano Profumo at the University of California, Santa Cruz, US. "So this is to be taken as a 'proof of principle' of a possible interpretation of the ARCADE excess, but not in any sense something that might point towards exotic origins such as dark-matter annihilation or decay."

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17 comments

80% - matter versus mass/energy

Several readers have questioned Jon's statement that dark matter is believed to make up more than 80% of the matter in the universe.

Please note that Jon has been very careful to use the word "matter" not "mass". It is true that dark energy is thought to comprise about 75% of the mass/energy in the universe, but Jon is referring specifically to matter, not mass/energy.

Several readers have questioned Jon's statement that dark matter is believed to make up more than 80% of the matter in the universe.

Please note that Jon has been very careful to use the word "matter" not "mass". It is true that dark energy is thought to comprise about 75% of the mass/energy in the universe, but Jon is referring specifically to matter, not mass/energy.

Actually it is predicted to be exactly 84% dark matter 16% ordinary matter.That together itself makes up 28.7% of the matter/energy of the Universe the rest 71.3%, is dark energy [1].

Enlightened matter

Come on guys, Dark matter only has to be made of electrons, (ions0 as being found from shocks (Cluster) to supercluster haloes. The refractive index of plasma (ions) is n=1 so its hardly surprising we consider them undetectable or 'dark!In fact they're not entirely undetectable, and the latest findings are consistent with Cluster and a dozen other results. Can we please start having some joined up physics.If the field is moving we get things like IFR, Stokes up and down shifted scattering, and the Kinetic Sunyaev-Zeldovitch effect, showing that each moving cloud of plasma represents an inertial frame, as a local field, normally via frame dragging by mass (shocks) just like Einstein predicted. We only need to drop a few nonsense assumptions and it all fits together.Surely we don't really believe all the conflicting mumbo jumbo.

In fact, isn't it a hint that plasma (as mainly free electrons) has always represented over 90% of the universe, and now we have worked out dark matter may represent something over 80% of the universe. Unless the universe totals some 170 of it's constituent parts then there may be a pre 'nucular' link the even George bush could see!

Dark Energy ~ Dark Mass? If c=1 then E=m!

Several readers have questioned Jon's statement that dark matter is believed to make up more than 80% of the matter in the universe.

Please note that Jon has been very careful to use the word "matter" not "mass". It is true that dark energy is thought to comprise about 75% of the mass/energy in the universe, but Jon is referring specifically to matter, not mass/energy.

An interesting conundrum. As energy itself is equivalent to mass. The difference between matter and mass is one of semantics, IMHO. One can't have matter without mass, no matter how minuscule. The question is though, can one have mass without matter, i.e. from energy.

I find the correlation between the the ratio of dark energy and the required ratio of dark mass striking.

What a confusion!

For a "flat universe", the different componenets of matter coming from different sources such the cmb fluctuations analysis are: ordinary matter: 4.6 %, dark matter: 23%, dark energy: 72%.Now, 80% of this 23% dark matter is cold dark matter and 20% is hot dark matter. However, the write-up says:" dark matter .... makes up more than 80% of the matter of the universe."Hamish, what can be more confusing than this? May be he was referring to this cold component of the dark matter?

Several readers have questioned Jon's statement that dark matter is believed to make up more than 80% of the matter in the universe.

Please note that Jon has been very careful to use the word "matter" not "mass". It is true that dark energy is thought to comprise about 75% of the mass/energy in the universe, but Jon is referring specifically to matter, not mass/energy.

IMO the universe exhibits blue shift in radiowave spectrum, i.e. at the wavelengths longer than the CMBR. This blue shift is followed with positive violation of inverse square law for distant radiowave sources. The similar violation of ISL can be observed at the case of asymmetric jets of black holes (virtual "jet suppression"). This model is already supported with some other observations, like the lack of ISW effect for dark matter galaxies (Shanks and Sawangwit) or blue shift of maser at the Pioneer 10 spacecraft (LaViolette).

BTW why this comment was deleted from there and previous comments about "autodynamics" not?

IMO the universe exhibits blue shift in radiowave spectrum, i.e. at the wavelengths longer than the CMBR. This blue shift is followed with positive violation of inverse square law for distant radiowave sources. The similar violation of ISL can be observed at the case of asymmetric jets of black holes (virtual "jet suppression"). This model is already supported with some other observations, like the lack of ISW effect for dark matter galaxies (Shanks and Sawangwit) or blue shift of maser at the Pioneer 10 spacecraft (LaViolette).

BTW why this comment was deleted from there and previous comments about "autodynamics" not?

In this comment suggest that “in your opinion” the radiowave spectrum is blue shifted. You might also suggest that the moon is made of green cheese.

Both suggestions are contradicted by observations. Astronauts did not find green cheese on the moon.

Radioastronomers find radiation from numerous sources in the universe is red-shifted because the universe is expanding.

The only observations of blue shifting have simple explanations. For example the Andromeda galaxy is moving towards the Milky Way galaxy within our own local group. Light from it is consequently blue shifted.

“in your opinion” the radiowave spectrum is blue shifted. You might also suggest that the moon is made of green cheese.

If follows from geometry of dispersion of light with CMBR noise. We have no reference sources in distant galaxies to observe the blue shift. In accordance with it has been observed that the galaxies are shrinking with time. Galaxies are large enough objects for radiowaves.

“in your opinion” the radiowave spectrum is blue shifted. You might also suggest that the moon is made of green cheese.

If follows from geometry of dispersion of light with CMBR noise. We have no reference sources in distant galaxies to observe the blue shift. In accordance with it has been observed that the galaxies are shrinking with time. Galaxies are large enough objects for radiowaves.

I suggest you submit your ideas to a reputable journal so they can be examined by knowledgable referees.

How many radio waves make five?

Well, to my mind, the picture says it all - the balloon is generating most - about 80% - of these high-frequency waves by rubbing against the Milky Way, with the rest - 20% or so - being the distorted reflection of radio and TV stations being reflected off all those galaxies and molecular clouds, and off those electron clouds (not illustrated). The FM-TV wave energy being up-converted to GHz frequencies by inverse scattering.

And just look out for the big bang when the balloon hits a spiky bit. I'm getting my hard hat out of cold (2.725K) storage right now...

Yes, I admit you are on point. See a copy of my e-mail to Mr.Flandern. He is correct and I agree with him... I hope the 'birds' at the scientific journals read his article to learn the difference between right or wrong- journals publish mostly garbage... May be the editor would strike this too...

I read the article on ‘big bang’ ? by Tom Van Flandern. Well written and convincing…, and I agree with most of it…On the Q of why ‘red-shift’ or ‘tired light’? I have a clear answer. Mr. Flandern as well as the rest of our-scientists (i.e the real scientists) will have to agree with my answer.By the way ‘big bang’, ‘expanding U’ or ‘dark energy’ is for the ‘birds’ as they say…And, the scientific journals are controlled by the ‘birds’, I must say…Please contact me, so- we can look into this further or may help resolve the issue..

The idea of "tired light" was considered long ago and ultimately rejected. This is the way of science.

This is the same story, like the heliocentric model, Duillier-LeSage gravity, dense aether model or cold fusion. The acceptance of ideas is alternating like the dispersive phenomena at the water surface. We already know, some aspects of tired light hypothesis are working. For example, the remote galaxies appear large, than these nearby ones. It's routinely explained with the dispersion of light at the CMBR flucuations, so that the question, how the wavelenght of light will change during this is quite legitimate.

The point is, the wavelength of light doesn't change during dispersion of light with the fog, so that this model isn't apparently able to explain the Hubble red shift. But the wavelenght is changing during dispersion of waves at the water surface and the resulting geometry fits the de Sitter geometry. The good point for the Big Bang theory is, this dispersion is consistent with the FRW metric and the time dimension can be constructed in the same way. Even better is, the dispersive model is able to predict/explain inflation and dark energy. The bad point for Big Bang theory is, it doesn't requires the initial singularity for it and it's basically relative to all places of observable Universe.

The idea of "tired light" was considered long ago and ultimately rejected. This is the way of science.

This is the same story, like the heliocentric model, Duillier-LeSage gravity, dense aether model or cold fusion. The acceptance of ideas is alternating like the dispersive phenomena at the water surface. We already know, some aspects of tired light hypothesis are working. For example, the remote galaxies appear large, than these nearby ones. It's routinely explained with the dispersion of light at the CMBR flucuations, so that the question, how the wavelenght of light will change during this is quite legitimate.

The point is, the wavelength of light doesn't change during dispersion of light with the fog, so that this model isn't apparently able to explain the Hubble red shift. But the wavelenght is changing during dispersion of waves at the water surface and the resulting geometry fits the de Sitter geometry. The good point for the Big Bang theory is, this dispersion is consistent with the FRW metric and the time dimension can be constructed in the same way. Even better is, the dispersive model is able to predict/explain inflation and dark energy. The bad point for Big Bang theory is, it doesn't requires the initial singularity for it and it's basically relative to all places of observable Universe.

I do not know what de Sitter geometry is- I did not look into that, because I knew he goofed in support to- Einstein GR, Sun-Earth control of Moon orbit, and Hubble expansion... By the way 'tired light' is not an appropriate word- an ignorant use. Yes light loses strength or heat- that's the reason CMB of ~2.7K. The wavelength increases with decrease of that K- so is the speed of light. Why K decreases and why wavelength increases? PLease wait until my work is published- because it is difficult to explain in few words, here. There is no dark energy; there was no big bang; there is no expansion of U...

From the same reason, from which the frequency of surface ripples decreases with distance and their wavelength increases during their spreading along water surface. It's because the portion of wave energy disperses into hidden extradimensions of space-time. When the surface ripple disperses, than the portion of their energy escapes from the 2D water surface into 3D underwater. It's general mechanism of spontaneous symmetry breaking.

The original tired light hypothesis didn't consider these extra-dimensions, so it cannot explain, why the light becomes reddish with shift of spectral lines. It predicted sorta red sky effect instead: it claimed, the remote galaxies should appear reddish, because the blue component is washed out from their light, i.e. without shift of spectral lines.

Sounds reasonable

From the same reason, from which the frequency of surface ripples decreases with distance and their wavelength increases during their spreading along water surface. It's because the portion of wave energy disperses into hidden extradimensions of space-time. When the surface ripple disperses, than the portion of their energy escapes from the 2D water surface into 3D underwater. It's general mechanism of spontaneous symmetry breaking.

The original tired light hypothesis didn't consider these extra-dimensions, so it cannot explain, why the light becomes reddish with shift of spectral lines. It predicted sorta red sky effect instead: it claimed, the remote galaxies should appear reddish, because the blue component is washed out from their light, i.e. without shift of spectral lines.

Yes, your explanation of wave-spreading in water sounds reasonable and OK to me. But, please let us forget spacetime- misuse of the term, and has no real meaning- except one can assign a meaning whatever one wishes at a given time... The Q- why light wave? Sure, loss of radiation in a given direction (2D) is a reason because as it spreads out like the water-wave it loses heat- but, there is more to it than that simple principle, we know...